Multiple Input, Multiple Output (“MIMO”) radar technology has emerged as a leading contender for advanced communication systems, including those being designed for millimeter wave applications in the 30 GHz to 300 GHz frequency spectrum. A MIMO radar employs multiple transmit antennas and has the ability to jointly process signals received at multiple receive antennas. Each transmit antenna transmits an independent waveform, which enables the MIMO radar to exploit increased degrees of freedom at the transmit array to improve resolution, flexibility, and adaptivity in comparison to conventional phase-array systems. Phase-array systems already possess several advantages over classical radar antennas based on their mechanical steering abilities with a wide Field-of-View (“FoV”). One of their shortcomings, however, is the degraded performance of phased-arrays when beams are steered to large angles. Not only is the antenna gain reduced significantly, but also the beam width is broadened. As a result, the FoV within which beam steering is performed with phase-array systems is usually limited to −120° to 120°.
During the last years new array antenna designs have been proposed and developed, including virtualization of radiating elements in receive mode. There have been several different ways to create virtual arrays and the main such techniques can be in two categories. The first one consists of creating duplicated receiver arrays using specifically placed multiple transmit antennas in MIMO configurations, which is also known as active virtual arrays. The second one, referred to as passive virtual arrays, create virtual receive arrays using a pair or multiple receiving antenna elements according to a specific geometry. In this category, a highly useful technique is to create virtual arrays from physical receive arrays using interpolation.